Create and use the access_mask_t typedef to enforce a consistent access mask size and uniformly use a 16-bits type. This will helps transition to a 32-bits value one day. Add a build check to make sure all (filesystem) access rights fit in. This will be extended with a following commit. Reviewed-by: Paul Moore <paul@xxxxxxxxxxxxxx> Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20220506161102.525323-2-mic@xxxxxxxxxxx --- Changes since v2: * Format with clang-format and rebase. Changes since v1: * Add Reviewed-by: Paul Moore. --- security/landlock/fs.c | 19 +++++++++++-------- security/landlock/fs.h | 2 +- security/landlock/limits.h | 2 ++ security/landlock/ruleset.c | 6 ++++-- security/landlock/ruleset.h | 16 ++++++++++++---- 5 files changed, 30 insertions(+), 15 deletions(-) diff --git a/security/landlock/fs.c b/security/landlock/fs.c index eeecf5b2fa89..d4006add8bdf 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -152,7 +152,8 @@ static struct landlock_object *get_inode_object(struct inode *const inode) * @path: Should have been checked by get_path_from_fd(). */ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset, - const struct path *const path, u32 access_rights) + const struct path *const path, + access_mask_t access_rights) { int err; struct landlock_object *object; @@ -184,7 +185,8 @@ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset, static inline u64 unmask_layers(const struct landlock_ruleset *const domain, const struct path *const path, - const u32 access_request, u64 layer_mask) + const access_mask_t access_request, + u64 layer_mask) { const struct landlock_rule *rule; const struct inode *inode; @@ -224,7 +226,8 @@ static inline u64 unmask_layers(const struct landlock_ruleset *const domain, } static int check_access_path(const struct landlock_ruleset *const domain, - const struct path *const path, u32 access_request) + const struct path *const path, + const access_mask_t access_request) { bool allowed = false; struct path walker_path; @@ -309,7 +312,7 @@ static int check_access_path(const struct landlock_ruleset *const domain, } static inline int current_check_access_path(const struct path *const path, - const u32 access_request) + const access_mask_t access_request) { const struct landlock_ruleset *const dom = landlock_get_current_domain(); @@ -512,7 +515,7 @@ static int hook_sb_pivotroot(const struct path *const old_path, /* Path hooks */ -static inline u32 get_mode_access(const umode_t mode) +static inline access_mask_t get_mode_access(const umode_t mode) { switch (mode & S_IFMT) { case S_IFLNK: @@ -565,7 +568,7 @@ static int hook_path_link(struct dentry *const old_dentry, get_mode_access(d_backing_inode(old_dentry)->i_mode)); } -static inline u32 maybe_remove(const struct dentry *const dentry) +static inline access_mask_t maybe_remove(const struct dentry *const dentry) { if (d_is_negative(dentry)) return 0; @@ -635,9 +638,9 @@ static int hook_path_rmdir(const struct path *const dir, /* File hooks */ -static inline u32 get_file_access(const struct file *const file) +static inline access_mask_t get_file_access(const struct file *const file) { - u32 access = 0; + access_mask_t access = 0; if (file->f_mode & FMODE_READ) { /* A directory can only be opened in read mode. */ diff --git a/security/landlock/fs.h b/security/landlock/fs.h index 03f746e74e9e..8db7acf9109b 100644 --- a/security/landlock/fs.h +++ b/security/landlock/fs.h @@ -66,6 +66,6 @@ __init void landlock_add_fs_hooks(void); int landlock_append_fs_rule(struct landlock_ruleset *const ruleset, const struct path *const path, - u32 access_hierarchy); + access_mask_t access_hierarchy); #endif /* _SECURITY_LANDLOCK_FS_H */ diff --git a/security/landlock/limits.h b/security/landlock/limits.h index a274ae6b5570..41372f22837f 100644 --- a/security/landlock/limits.h +++ b/security/landlock/limits.h @@ -9,6 +9,7 @@ #ifndef _SECURITY_LANDLOCK_LIMITS_H #define _SECURITY_LANDLOCK_LIMITS_H +#include <linux/bitops.h> #include <linux/limits.h> #include <uapi/linux/landlock.h> @@ -19,6 +20,7 @@ #define LANDLOCK_LAST_ACCESS_FS LANDLOCK_ACCESS_FS_MAKE_SYM #define LANDLOCK_MASK_ACCESS_FS ((LANDLOCK_LAST_ACCESS_FS << 1) - 1) +#define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS) /* clang-format on */ diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index 4d33359addbd..996484f98bfd 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -45,7 +45,8 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) return new_ruleset; } -struct landlock_ruleset *landlock_create_ruleset(const u32 fs_access_mask) +struct landlock_ruleset * +landlock_create_ruleset(const access_mask_t fs_access_mask) { struct landlock_ruleset *new_ruleset; @@ -228,7 +229,8 @@ static void build_check_layer(void) /* @ruleset must be locked by the caller. */ int landlock_insert_rule(struct landlock_ruleset *const ruleset, - struct landlock_object *const object, const u32 access) + struct landlock_object *const object, + const access_mask_t access) { struct landlock_layer layers[] = { { .access = access, diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index e9ba47045aca..8d5717594931 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -9,13 +9,20 @@ #ifndef _SECURITY_LANDLOCK_RULESET_H #define _SECURITY_LANDLOCK_RULESET_H +#include <linux/bitops.h> +#include <linux/build_bug.h> #include <linux/mutex.h> #include <linux/rbtree.h> #include <linux/refcount.h> #include <linux/workqueue.h> +#include "limits.h" #include "object.h" +typedef u16 access_mask_t; +/* Makes sure all filesystem access rights can be stored. */ +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS); + /** * struct landlock_layer - Access rights for a given layer */ @@ -28,7 +35,7 @@ struct landlock_layer { * @access: Bitfield of allowed actions on the kernel object. They are * relative to the object type (e.g. %LANDLOCK_ACTION_FS_READ). */ - u16 access; + access_mask_t access; }; /** @@ -135,19 +142,20 @@ struct landlock_ruleset { * layers are set once and never changed for the * lifetime of the ruleset. */ - u16 fs_access_masks[]; + access_mask_t fs_access_masks[]; }; }; }; -struct landlock_ruleset *landlock_create_ruleset(const u32 fs_access_mask); +struct landlock_ruleset * +landlock_create_ruleset(const access_mask_t fs_access_mask); void landlock_put_ruleset(struct landlock_ruleset *const ruleset); void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset); int landlock_insert_rule(struct landlock_ruleset *const ruleset, struct landlock_object *const object, - const u32 access); + const access_mask_t access); struct landlock_ruleset * landlock_merge_ruleset(struct landlock_ruleset *const parent, -- 2.35.1
